One common treatment for male erectile dysfunction includes the implantation of a penile implant device. One type of penile implant device includes a pair of cylindrical prostheses that are implanted into the corpus cavernosae of the penis. Typically, the cylindrical prostheses or cylinders are inflatable and are connected to a fluid-filled reservoir through a pump and valve assembly. With one such type of system, one tube extends from each of the two cylindrical prostheses and connects to the pump, and one tube connects the pump to the reservoir. The pump is typically surgically implanted into the scrotum of the patient and the reservoir is implanted in the abdomen, with the tubes fluidly connecting the components. To activate the penile implant device, the patient actuates the pump using one of a variety of methods that cause fluid to be transferred from the reservoir through the pump and into the cylindrical prostheses. This results in the inflation of the prostheses and produces rigidity for a normal erection. Then, when the patient desires to deflate the prostheses, a valve assembly within the pump is actuated in a manner such that the fluid in the prostheses is released back into the reservoir. This deflation returns the penis to a flaccid state.
It is desirable that both the radial and longitudinal expansion of the cylindrical prosthesis be accommodated to constrain and prevent over-expansion.